System.Collections.Specialized.OrderedDictionary.this C# (CSharp) Method

        public object this[object key]
        {
            get
            {
                return objectsTable[key];
            }
            set
            {
                if (_readOnly)
                {
                    throw new NotSupportedException(SR.OrderedDictionary_ReadOnly);
                }
                if (objectsTable.Contains(key))
                {
                    objectsTable[key] = value;
                    objectsArray[IndexOfKey(key)] = new DictionaryEntry(key, value);
                }
                else
                {
                    Add(key, value);
                }
            }
        }